This invention relates to building elements useful in constructing boat hulls, for example, and is concerned with methods and apparatus for making the building element and for using it to construct various objects.
Boat hulls have been made of glass fibers impregnated with resin to hold the fibers together, but such hulls have required a high proportion of resin and are heavier and weaker than if it were possible to use a higher percentage of fibers. Glass fibers are much stronger and lighter than resin. Also, previous glass fiber hulls have been constructed of glass fiber mats which are more expensive than glass fiber roving.
Another problem in producing glass fiber building elements has been caused by the fast drying of the adhesive resin which dried very rapidly in about fifteen to thirty minutes so that the stamp elements had to be made in batch fashion so as to use a batch of adhesive resin before it dried up.
Glass fiber building elements made from woven glass fiber roving or mats trap air when being impregnated with resin and this air is very difficult to remove by rolling in the lay-up process, and if the air is not removed the building element is pourous and weak.
Moreover, conventional glass fiber elements are strong in the direction of the fiber strands but are weak in the transverse direction. See Analysis of Composite Structures, Tsai et al., NASA Contractor Report, NASA CR-620, November 1966.